function [annul_default_rate]=actual_default(bad_debt_interest,Tot_default,recover_rate,year_work)
bad_debt_interest=bad_debt_interest/100;
Tot_default=Tot_default/100;
recover_rate=recover_rate/100;

total_default=Tot_default+bad_debt_interest/recover_rate;
annul_default_rate=1-(1-total_default)^(1/year_work);
